Claude Fable 5.1

Claude Fable 5.1 is Anthropic’s active flagship model for demanding reasoning and long-horizon agentic work. It accepts text and image input and produces text output.

It is designed for long-running agentic coding, multistep research, and complex work with documents, spreadsheets, and slides.

It offers a 1-million-token context window, up to 128K output tokens, vision, tool use, and always-on adaptive thinking controlled through effort settings.

Anthropic labels its comparative latency as slower, and its per-token price is higher than Claude Opus 5 or Sonnet 5. Adaptive thinking cannot be disabled, and safety classifiers can return a refusal, so test latency, cost, and refusal handling.

Use the model identifier claude-fable-5-1 in your TokenHub API request, together with the endpoint and credentials shown in your TokenHub account. Test request formatting and response handling before production use.

Anthropic lists Claude Fable 5.1 as active on the Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS. Published Claude API rates are $10 per million input tokens, $50 per million output tokens, and $0.25 per million cache-read tokens; TokenHub billing may differ.

Choose it when difficult, long-horizon work needs more capability than your evaluations get from Claude Opus 5 at higher effort. For most routine workloads, Anthropic recommends starting with Claude Opus 5, while faster or cheaper models may be better for high-volume tasks.